先化简,再求值(x+y/2)^2-(x-y/2)^2,其中x=-1/16,y=8
问题描述：
先化简,再求值(x+y/2)^2-(x-y/2)^2,其中x=-1/16,y=8
答
化简得xy. 结果是-1/2.
答
(x+y/2)^2-(x-y/2)^2
=[(x+y/2)+(x-y/2)][(x+y/2)-(x-y/2)]
=2x*2*y/2
=2xy
=2*(1/16)*8
=1
答
(x+y/2)^2-(x-y/2)^2
=(x+y/2+x-y/2)(x+y/2-x+y/2)
=2x*y=2xy
x=-1/16,y=8时
2xy=2*(-1/16)*8
=-1
答
1